Connecting units of the above type are known in which the connectors comprise respective insulating casings defining respective numbers of cavities for housing respective connectable male and female electric terminals.
Such units normally comprise a lever-and-slide coupling device, which is operated manually when the plug and socket connectors are engaged to couple the connectors with a minimum amount of effort.
The lever-and-slide coupling device substantially comprises a slide fitted to slide inside the plug connector casing in a direction perpendicular to the coupling direction of the connectors; and an actuating lever hinged to the plug connector casing and connected to the slide.
In a fairly common embodiment, the slide is C-shaped and defined by an end wall perpendicular to the sliding direction, and by two lateral walls extending perpendicularly from respective opposite end edges of the end wall, and which slide along respective lateral walls of the plug connector casing. Each lateral wall of the slide has a number of cam grooves for receiving respective external pins on the socket connector, and for producing a relative engaging movement of the plug and socket connectors in the coupling direction when the slide is moved in the sliding direction.
The slide is normally retained, by releasable retaining means, e.g. click-on retaining members, in a preassembly position partly inserted inside the plug connector casing, and is moved into a fully inserted position inside the casing by rotating the actuating lever from a raised to a lowered position about its hinge axis.
To function properly, the releasable retaining means must be sized and designed to ensure a given load by which to retain the slide inside the casing.
The load, however, may not be sufficient to prevent the slide from being inserted accidentally inside the plug connector casing, in the event the plug connector is knocked, dropped, etc. before being coupled to the complementary connector. In which case, the slide must be reset to the preassembly position before the connectors are coupled, thus complicating assembly of the connecting unit.
By way of a solution to the problem, the load exerted by the retaining means could be increased, though this would also mean a corresponding increase in the force required on the actuating lever to couple the connectors, thus impairing the function for which the lever-and-slide coupling device was designed, i.e. to permit coupling of the connectors with a minimum amount of effort.